Head for cartridge actuated catapult



United States Patent HEAD FOR CARTRIDGE ACTUATED CATAPULT C Walter Musser, Beverly, Mass., and Albert M. Stott,

Aldan-Clifton-Heights, and Albert Benditt, Philadelphia, Pa., assignors to the United States of America as represented by the Secretary of the Army Application August 10, 1956, Serial No. 603,456

2 Claims. (Cl. 89-1) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without payment of any royalty thereon.

This invention relates to a cartridge actuated device such as a catapult of the type used on airplanes for ejecting personnel therefrom. An object is to provide a device of this sort which is safer in event of breakage of the sear holding a cartridge actuating firing pin from prematurely firing the device. Another object is to enhance reliability by causing the firing pin to deliver a stronger hammer blow upon the cartridge device actuating the catapult.

Heretofore, the sear for holding a main firing pin retracted had to be fragile. This presented the danger of accidental rupture resulting in accidental firing of the catapult or other device. According to this invention a spring forcing the firing pin toward a cartridge for actuating the device is normally retained under a greatly reduced pre-load so that, in event the firing pin should be released, there will be little or no danger of the main cartridge being fired by reason of the comparatively small pre-load of the firing pin spring.

It has been found that the danger of misfire in the main cartridge may be reduced by providing a stronger hammer blow by the firing pin. Specifically, this has been made possible by providing a fluid pressure responsive plunger actuated by another source of pressure or an auxiliary cartridge. The plunger encloses the firing pin spring and kinetic energy of the plunger is transferred to the firing pin at the time of its release to deliver a stronger impact upon the main cartridge device. Preferably, the spring is fully compressed as the firing pin is released so that the kinetic energy of the plunger is the better able to be transferred to the firing pin upon its release. No substantial dwell occurs just before the release of the firing pin.

Referring to the drawings,

Fig. 1 is a longitudinal section through a preferred embodiment of the present invention with the sear in locking position prior to release of the firing pin and before the spring has begun to be compressed by fluid pressure.

Fig. 2 is a view partly in seciton taken on the olfset line 2-2 of Fig. 1.

Fig. 3 is a view of the device of Fig. 1 as the sear is releasing the firing pin and while the spring is fully compressed.

Fig. 4 is a view somewhat similar to Fig. 1 but showing the sear after release of the firing pin and firing the main cartridge.

Fig. 5 is a view on the line 5-5 of Fig. 1.

Fig. 6 is a view of the sear alone as viewed from the left side of it in Fig. 1.

Fig. 7 shows the sear of Fig. 6 as viewed from the top.

Fig. 8 is a view of the sear end in locked position in the slot in the outer tube.

Fig. 9 shows the sear end when in unlocked position after release of the firing pin.

Fig. 10 shows the sear end after it and the head have been disengaged from the outer tube.

Fig. 11 shows the assembly lock pin 19A.

The head 12 for a cartridge actuated catapult fits into an outer tube 11 of the catapult secured to the head 12. The usual mounting hole for attachment is shown at the upper part of the head. A hose from an auxiliary cartridge actuated device is attached to the head at 13, the gas from the auxiliary device entering the head and acting upon one end of a plunger 16. A firing pin, or more properly, a firing pin body 14 is restrained against movement prematurely by a sear 17. A spring 15 cooperates at one end with the firing pin body and at its other end with the plunger 16. The scar 17 is provided with a tongue 18 engaging one end of the firing pin body 14. An assembly locking pin, when inserted in hole 19, retains the firing pin within the plunger 16 and head 12. A pair of coplanar flat guide surfaces 20 on the plunger 16 are arranged on each side of the tongue 18 as shown in Figs. 2, 3, and 4. Cooperative flat guide surfaces 21 are on the sear. A recess 23 in the plunger has sloping flat guide surfaces 22 with which the sear flat guide surfaces 21 cooperate after release of the firing pin. The scar 17 is provided with a cutaway portion 24 of the shape illustrated in Figs. 5, 6 and 7 for the purpose of avoiding frictional engagement with the plunger 16 and the spring 15 after release of the firing pin 14 by the sear. The extreme end portions 26 of the sear engage within open end slots 25 in the outer tube 11 and constitute the locking element for securing the head 12 to this outer tube 11 prior to release of the firing pin. These end portions 26 of the sear are in the position shown in Fig. 8 when the head is locked to the tube 11. These end portions 26 are in the position shown in Fig. 9 when the sear has been rotated to an unlocking position for release of the firing pin and also to permit disengagement of the head from the tube 11. A longitudinal slot 29 is formed in one side of the plunger in order to permit the assembly locking pin to extend therethrough into the firing pin 14 for the purpose of retaining the firing pin after insertion of the sear 17. But after the sear has been rotated so that tang 18 engages firing pin 14 the assembly locking pin is removed in order that slight pre-load in the spring 15 may be borne by the sear. The portions 30 of the sear (Figs. 2, 5 and 7) bear within holes or hearings in the head 12. The longitudinal travel of the plunger 16 between initiation of its movement under cartridge fluid pressure from the auxiliary device is indicated by the numeral 31 in Fig. 3, the same being the extent of its travel until the firing pin has been released.

To assemble the head: (a) The plunger 16 is partially inserted into the head (b) The scar 17 is inserted through the head 12 and the recess 23 in plunger 16 and oriented to pass spring 15;

(c) The spring 15 is inserted into plunger 16;

(d) The firing pin 14 is inserted into plunger 16 and the spring 15 is compressed until a locking pin 19A can be inserted into the hole in firing pin 14 to hold the assembly into place until inserted into a catapult.

When the aforementioned head assembly is ready to be inserted into a catapult the sear ends 26 will be in the position shown in Fig. 8 preventing introduction of said sear ends in slot 25 of the catapult outer tube 11. To rotate the sear end 26 so that head assembly can be attached to the catapult the procedure as outlined below must be followed:

Air pressure is introduced through opening 13 in head 12 moving plunger 16 toward the firing pin 14 and compressing spring 15. Even though the firing pin is se- 'curely held in position by the locking pin 19A, which passes through the plunger 16, the plunger is capable of moving under the air pressure because of the configuration of the hole 29 (Fig. 2) in the plunger and the locking pin 19B (see Fig. 11). When the plunger has moved to the limit of its travel the locking pin cannot be removed inadvertently, because of the aforementioned configuration, thus preventing travel of the full, loaded firing pin.

With the plunger at the limit of its travel the sear can be readily rotated so that its ends assume the position shown in Fig. 9 permitting the said ends to be inserted in slot 25. When the assembly is in place the air pressure is removed permitting the plunger to return to its normal position. The plunger in doing so will rotate the seal and its ends will again assume the position shown in Fig. 8 securely locking the parts together. At this time the assembly locking pin may be withdrawn so that only the sear restrains the firing pin 14 under slight load.

Upon actuation of the auxiliary cartridge device, the plunger 16 is moved under gas pressure compressing the spring 15. The spring 15 becomes fully or completely compressed with its coils contiguous one another just before the firing pin is released. As the plunger is moved down by the gas pressure, the coplanar guide surfaces 20 slide on the guide surfaces 21 of the scar and since these surfaces are each flat, rotation of the sear is precluded at this time. The firing pin 14 is held by the tongue 18 of the sear until the motion of the plunger has progressed far enough for the sear to be able to tilt or slightly rotate into the recess 23 in the plunger. At this time, the tongue 18 of the sear is moved away allowing the firing pin to be moved under spring pressure and also under the kinetic energy of the moving plunger. At the time of this partial rotation of the sear, the cutaway portion 24 prevents the sear from frictionally engaging or impeding the movement of the spring 15. Also, at the time of this partial rotation of the sear, the ends 26 of the sear move from the position shown in Fig. 8 to the position shown in Fig. 9 when the end portions 26 of the sear are able to slide out of the hollow end of the tube 11 and release the head 12 from the tube 11. The flat guide surfaces 21 of the sear 17 engage the flat guide surfaces 22 of recess 23 to prevent the sear rotating more than the desired amount.

Among the advantages of this invention may be mentioned first the greater safety that accrues from having the spring 15 only slightly stressed normally and prior to the firing of the auxiliary cartridge actuated device. The advantage of this construction is that in the event the tongue 18 should rupture, the firing pin when released will not be in danger of actuating the main cartridge prior to firing the auxiliary cartridge device. Another advantage of the present invention is the harder blow that is struck by the firing pin upon the main cartridge actuated device. This harder blow results from at least two causes. One, is the usual energy imparted to the firing pin by its spring 15. In addition, the spring 15 is fully compressed prior to release of the firing pin with the result that the kinetic energy of the moving plunger 16 also is transmitted to a substantial extent to the firing pin for the purpose just described. The full compression of the spring does not result in any objectionable or substantial period of dwell since the plunger is moving under fluid pressure and the sear is enabled to tilt into recess 23 after the plunger has traversed a predetermined linear travel.

We claim:

1. In a cartridge actuated device having an outer tube, a head closing one end of said outer tube, a hollow cylindrical plunger closed at its outer end, a hollow cylindrical projection on said head, said projection closed at its outer end and guiding said plunger, a firing pin slidable within said plunger, a rotatable sear for holding said firing pin against movement to its firing position, an extension on said sear for locking said head to the outer tube, an initially compressed spring between said firing pin and said plunger, the combination therewith of the improvement for further compressing said spring and rotating said sear releasing the firing pin and unlocking the head from the outer tube, said improvement comprising a rigid tongue on the sear for holding the firing pin against movement to its firing position, a fluid pressure connection to said projection for applying fluid pressure to the plunger, said plunger being provided with a longitudinal recess, the side walls of said recess being flattened to engage a flattened portion of the sear for holding the sear against premature rotation, the outer end position of said recess being enlarged to allow rotation of said sear for releasing the firing pin and unlocking said head from the outer tube when the plunger has been moved inward by fluid pressure far enough for the sear which is being held against rotation to engage said recess enlargement and rotate releasing the firing pin and unlocking the head from the outer tube, whereby the distance moved by the plunger prior to rotation of the sear determining the degree of additional compression applied to the spring before release of the firing pin.

2. In a combination according to claim 1 of the improvement for enhancing safety under initial spring compression, said improvement having said firing pin spring initially compressed with a stress incapable of detonation a cartridge actuated device by premature release of the firing pin in event of scar rupture, said precompression of said spring being determined by the closed end of the plunger engaging the outer end of the cylindrical projection on the head.

References Cited in the file of this patent UNITED STATES PATENTS 1,514,743 Taylor Nov. 11, 1924 2,505,000 Moore Apr. 25, 1950 2,580,483 Summerbell Jan. 1, 1952 2,726,055 Musser Dec. 6, 1955 

